diff --git a/package.json b/package.json
index 3d3d938b..6a5a47a1 100644
--- a/package.json
+++ b/package.json
@@ -60,7 +60,7 @@
     "i18next-http-backend": "^1.4.4",
     "livekit-client": "1.12.0",
     "lodash": "^4.17.21",
-    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#d79d9ae69c3220c02406706d4a1ec52c22c44fbd",
+    "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#b698217445318f453e0b1086364a33113eaa85d9",
     "matrix-widget-api": "^1.3.1",
     "mermaid": "^8.13.8",
     "normalize.css": "^8.0.1",
diff --git a/src/ClientContext.tsx b/src/ClientContext.tsx
index d488d6de..69a9295e 100644
--- a/src/ClientContext.tsx
+++ b/src/ClientContext.tsx
@@ -327,10 +327,6 @@ async function loadClient(): Promise<InitResult> {
 
       logger.log("Using a standalone client");
 
-      const foci = Config.get().livekit
-        ? [{ livekitServiceUrl: Config.get().livekit!.livekit_service_url }]
-        : undefined;
-
       /* eslint-disable camelcase */
       const { user_id, device_id, access_token, passwordlessUser } = session;
       const initClientParams = {
@@ -339,7 +335,7 @@ async function loadClient(): Promise<InitResult> {
         userId: user_id,
         deviceId: device_id,
         fallbackICEServerAllowed: fallbackICEServerAllowed,
-        foci,
+        livekitServiceURL: Config.get().livekit!.livekit_service_url,
       };
 
       try {
diff --git a/src/livekit/OpenIDLoader.tsx b/src/livekit/OpenIDLoader.tsx
index 66b5cc76..911a1ae7 100644
--- a/src/livekit/OpenIDLoader.tsx
+++ b/src/livekit/OpenIDLoader.tsx
@@ -22,6 +22,7 @@ import {
   useState,
 } from "react";
 import { logger } from "matrix-js-sdk/src/logger";
+import { GroupCall } from "matrix-js-sdk";
 
 import {
   OpenIDClientParts,
@@ -32,7 +33,7 @@ import { ErrorView, LoadingView } from "../FullScreenView";
 
 interface Props {
   client: OpenIDClientParts;
-  livekitServiceURL: string;
+  groupCall: GroupCall;
   roomName: string;
   children: ReactNode;
 }
@@ -41,12 +42,7 @@ const SFUConfigContext = createContext<SFUConfig | undefined>(undefined);
 
 export const useSFUConfig = () => useContext(SFUConfigContext);
 
-export function OpenIDLoader({
-  client,
-  livekitServiceURL,
-  roomName,
-  children,
-}: Props) {
+export function OpenIDLoader({ client, groupCall, roomName, children }: Props) {
   const [state, setState] = useState<
     SFUConfigLoading | SFUConfigLoaded | SFUConfigFailed
   >({ kind: "loading" });
@@ -56,7 +52,7 @@ export function OpenIDLoader({
       try {
         const result = await getSFUConfigWithOpenID(
           client,
-          livekitServiceURL,
+          groupCall,
           roomName
         );
         setState({ kind: "loaded", sfuConfig: result });
@@ -65,7 +61,7 @@ export function OpenIDLoader({
         setState({ kind: "failed", error: e as Error });
       }
     })();
-  }, [client, livekitServiceURL, roomName]);
+  }, [client, groupCall, roomName]);
 
   switch (state.kind) {
     case "loading":
diff --git a/src/livekit/openIDSFU.ts b/src/livekit/openIDSFU.ts
index 88adcc70..3cc61fbb 100644
--- a/src/livekit/openIDSFU.ts
+++ b/src/livekit/openIDSFU.ts
@@ -14,9 +14,11 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { MatrixClient } from "matrix-js-sdk";
+import { GroupCall, IOpenIDToken, MatrixClient } from "matrix-js-sdk";
 import { logger } from "matrix-js-sdk/src/logger";
 
+import { Config } from "../config/Config";
+
 export interface SFUConfig {
   url: string;
   jwt: string;
@@ -30,25 +32,84 @@ export type OpenIDClientParts = Pick<
 
 export async function getSFUConfigWithOpenID(
   client: OpenIDClientParts,
-  livekitServiceURL: string,
+  groupCall: GroupCall,
   roomName: string
 ): Promise<SFUConfig> {
   const openIdToken = await client.getOpenIdToken();
   logger.debug("Got openID token", openIdToken);
 
-  const res = await fetch(livekitServiceURL + "/sfu/get", {
-    method: "POST",
-    headers: {
-      "Content-Type": "application/json",
-    },
-    body: JSON.stringify({
-      room: roomName,
-      openid_token: openIdToken,
-      device_id: client.getDeviceId(),
-    }),
-  });
-  if (!res.ok) {
-    throw new Error("SFU Config fetch failed with status code " + res.status);
+  // if the call has a livekit service URL, try it.
+  if (groupCall.livekitServiceURL) {
+    try {
+      logger.info(`Trying to get JWT from ${groupCall.livekitServiceURL}...`);
+      const sfuConfig = await getLiveKitJWT(
+        client,
+        groupCall.livekitServiceURL,
+        roomName,
+        openIdToken
+      );
+
+      return sfuConfig;
+    } catch (e) {
+      logger.warn(
+        `Failed to get JWT from group call's configured URL of ${groupCall.livekitServiceURL}.`,
+        e
+      );
+    }
+  }
+
+  // otherwise, try our configured one and, if it works, update the call's service URL in the state event
+  // NB. This wuill update it for everyone so we may end up with multiple clients updating this when they
+  // join at similar times, but we don't have a huge number of options here.
+  const urlFromConf = Config.get().livekit!.livekit_service_url;
+  logger.info(`Trying livekit service URL from our config: ${urlFromConf}...`);
+  try {
+    const sfuConfig = await getLiveKitJWT(
+      client,
+      urlFromConf,
+      roomName,
+      openIdToken
+    );
+
+    logger.info(`Updating call livekit service URL with: ${urlFromConf}...`);
+    try {
+      await groupCall.updateLivekitServiceURL(urlFromConf);
+    } catch (e) {
+      logger.warn(
+        `Failed to update call livekit service URL: continuing anyway.`
+      );
+    }
+
+    return sfuConfig;
+  } catch (e) {
+    logger.error("Failed to get JWT from URL defined in Config.", e);
+    throw e;
+  }
+}
+
+async function getLiveKitJWT(
+  client: OpenIDClientParts,
+  livekitServiceURL: string,
+  roomName: string,
+  openIDToken: IOpenIDToken
+): Promise<SFUConfig> {
+  try {
+    const res = await fetch(livekitServiceURL + "/sfu/get", {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify({
+        room: roomName,
+        openid_token: openIDToken,
+        device_id: client.getDeviceId(),
+      }),
+    });
+    if (!res.ok) {
+      throw new Error("SFU Config fetch failed with status code " + res.status);
+    }
+    return await res.json();
+  } catch (e) {
+    throw new Error("SFU Config fetch failed with exception " + e);
   }
-  return await res.json();
 }
diff --git a/src/room/GroupCallView.tsx b/src/room/GroupCallView.tsx
index 9afc2ec3..29d14b82 100644
--- a/src/room/GroupCallView.tsx
+++ b/src/room/GroupCallView.tsx
@@ -36,7 +36,6 @@ import { UserChoices } from "../livekit/useLiveKit";
 import { findDeviceByName } from "../media-utils";
 import { OpenIDLoader } from "../livekit/OpenIDLoader";
 import { ActiveCall } from "./InCallView";
-import { Config } from "../config/Config";
 
 declare global {
   interface Window {
@@ -219,20 +218,13 @@ export function GroupCallView({
     undefined
   );
 
-  const livekitServiceURL =
-    groupCall.foci[0]?.livekitServiceUrl ??
-    Config.get().livekit?.livekit_service_url;
-  if (!livekitServiceURL) {
-    return <ErrorView error={new Error("No livekit_service_url defined")} />;
-  }
-
   if (error) {
     return <ErrorView error={error} />;
   } else if (state === GroupCallState.Entered && userChoices) {
     return (
       <OpenIDLoader
         client={client}
-        livekitServiceURL={livekitServiceURL}
+        groupCall={groupCall}
         roomName={`${groupCall.room.roomId}-${groupCall.groupCallId}`}
       >
         <ActiveCall
diff --git a/src/widget.ts b/src/widget.ts
index a7ea1b0f..93107fcd 100644
--- a/src/widget.ts
+++ b/src/widget.ts
@@ -164,7 +164,7 @@ export const widget: WidgetHelpers | null = (() => {
           // message so that we can use the widget API in less racy mode, but we need to change
           // element-web to use waitForIFrameLoad=false. Once that change has rolled out,
           // we can just start the client after we've fetched the config.
-          foci: [],
+          livekitServiceURL: undefined,
         }
       );
 
@@ -178,9 +178,7 @@ export const widget: WidgetHelpers | null = (() => {
           // Now we've fetched the config, be evil and use the getter to inject the focus
           // into the client (see above XXX).
           if (focus) {
-            client.getFoci().push({
-              livekitServiceUrl: livekit.livekit_service_url,
-            });
+            client.setLivekitServiceURL(livekit.livekit_service_url);
           }
           await client.startClient();
           resolve(client);
diff --git a/yarn.lock b/yarn.lock
index 7073bdf9..d8207984 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2187,9 +2187,9 @@
     clsx "^1.2.1"
 
 "@matrix-org/matrix-sdk-crypto-js@^0.1.1":
-  version "0.1.2"
-  resolved "https://registry.yarnpkg.com/@matrix-org/matrix-sdk-crypto-js/-/matrix-sdk-crypto-js-0.1.2.tgz#b58679e161f3d734359a8665922956309b1a4417"
-  integrity sha512-bbal0RcWwerS/DgqhOgM7wkXJ2YSv9fySK/qgLlrAsdYLpMSTqG8wDQ89/v+RYo9WmA5hwUN/wXcCDdFaFEXQQ==
+  version "0.1.3"
+  resolved "https://registry.yarnpkg.com/@matrix-org/matrix-sdk-crypto-js/-/matrix-sdk-crypto-js-0.1.3.tgz#19981e7613d3673d07c885a98d39276b5fe74ef0"
+  integrity sha512-RcRlE3wcMnE5ijACHIHmhXFogEEJdIcb/CbJ4rK1PCMduQ4yvxycVpMxwh7aKxFNitZbHZLCK7TfRzUpzjU2tw==
 
 "@matrix-org/olm@https://gitlab.matrix.org/api/v4/projects/27/packages/npm/@matrix-org/olm/-/@matrix-org/olm-3.2.14.tgz":
   version "3.2.14"
@@ -11012,9 +11012,9 @@ matrix-events-sdk@0.0.1:
   resolved "https://registry.yarnpkg.com/matrix-events-sdk/-/matrix-events-sdk-0.0.1.tgz#c8c38911e2cb29023b0bbac8d6f32e0de2c957dd"
   integrity sha512-1QEOsXO+bhyCroIe2/A5OwaxHvBm7EsSQ46DEDn8RBIfQwN5HWBpFvyWWR4QY0KHPPnnJdI99wgRiAl7Ad5qaA==
 
-"matrix-js-sdk@github:matrix-org/matrix-js-sdk#d79d9ae69c3220c02406706d4a1ec52c22c44fbd":
+"matrix-js-sdk@github:matrix-org/matrix-js-sdk#b698217445318f453e0b1086364a33113eaa85d9":
   version "26.2.0"
-  resolved "https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/d79d9ae69c3220c02406706d4a1ec52c22c44fbd"
+  resolved "https://codeload.github.com/matrix-org/matrix-js-sdk/tar.gz/b698217445318f453e0b1086364a33113eaa85d9"
   dependencies:
     "@babel/runtime" "^7.12.5"
     "@matrix-org/matrix-sdk-crypto-js" "^0.1.1"